The computer mouse has been the primary vehicle for users to control the movement of a cursor on a screen. One reason for this is that the action of the mouse uses very natural processes in the brain. The “point and click” sequence of moving the cursor to the desired position and depressing a button to select an action uniquely utilizes the existing brain pathways established over many years. Although the mouse has the physiological advantage among positioning devices because of its accurate feel and ease of use, it has disadvantages—principally in the amount of desk space required and in the fact that the hands must be removed from the keyboard to use the mouse. In addition, injuries have been recorded based on reaching an awkward distance to access the mouse or positioning the mouse at an incorrect height for ergonomic operation. It would be advantageous to eliminate the disadvantages associated with using a computer mouse.
Alternate positioning devices that have been developed to replace the mouse include the trackball, the touchpad, the joystick, the touch sensitive screen and devices tailored for particular applications. The touch sensitive screen and joystick do not address the issue of keeping the hands engaged with the keyboard. The trackball, touchpad and other special devices have typically been integrated into a special keyboard in order to keeping the hands in typing position. Nonetheless, users have not adopted these devices as readily as they have the mouse.
Rollerbar devices have been developed that relied on separate sensors to sense rotational and translational movement of a bar. These have not met with great success. One device retained the mouse and its interface to the computer but adapted it to a rollerbar configuration. This device captured the mouse in a pad that placed a rollerbar under the mouse's ball. As the rollerbar moved, it moved the mouse ball so that the mouse sent the appropriate signals to the computer. The rollerbar could be positioned directly abutting the keyboard space bar. In addition to the rollerbar under the mouse ball, the device incorporated a pair of movable pads that were connected to the mouse buttons. By depressing the pads, the mouse buttons were depressed. While this device worked, it did not accommodate all computer mouses and did not have the intuitive feel of the mouse.
A positioning device that is controllable while the hands remain on the keyboard in order to increase productivity is needed. In addition, the positioning device should minimize strain on wrist and shoulder while providing fast and precise positioning functions as an add-on to existing keyboards.